Field of the Invention
This invention relates to the use of cementing plugs, balls, darts and other elements in the cementing of casing in oil and gas wells. More specifically, the invention relates to the remote controlled injection of cementing plugs into casing and/or drill pipe (hereinafter referred to as well pipe) which is hung in a well prior to the cementing operation and to displacement of cement from the well pipe after the cementing process has been completed. The remotely controlled cementing plug container of this invention is designed to release a bottom cementing plug as an interface between the drilling fluid and the cement by opening an air or hydraulic cylinder valve on a control panel remotely located from the cementing plug container and introducing a suitable fluid into the cementing plug container. The bottom cementing plug wipes the drilling fluid from the walls of the well pipe ahead of the cement slurry, reducing dilution. Upon completion of the cementing operation the cementing plug container is again remotely operated to drop a top cementing plug responsive to manipulation of a second air or hydraulic cylinder valve. The function of this plug is to follow the cement and prevent contamination or channeling of the cement with drilling fluid or other fluid used to displace the cement. The cementing plug container is operated to inject the bottom and top cementing plugs from the container housing into the well pipe at specified time intervals by operation of air or hydraulic cylinders responsive to manipulation of the remotely located air or hydraulic cylinder valves cooperating with the air or hydraulic cylinders. The apparatus of this invention is further characterized by a plug pass indicator which positively and both remotely and mechanically indicates when a plug or plugs have passed from the interior of the cementing plug container housing through the bore of the housing. The cementing plug container is specifically designed to quickly, efficiently and inexpensively inject one or more cementing plugs into a length of well pipe in an oil or gas well, both before and after the well pipe cementing operation and to verify that the plugs have been injected into the well pipe by using a control panel located some distance from the well, in order to minimize the time and cost of cementing the well pipe in the well and to maximize safety during the cementing operation.